BACKGROUND AND OBJECTIVE: The incidence and clinical impact of perioperative myocardial infarction during coronary artery bypass graft surgery vary greatly depending upon the diagnostic criteria applied. Fatal perioperative myocardial infarction has a less arguable diagnosis and clinical impact. The aim of this paper is to find out the risk factors for fatal myocardial infarction after coronary surgery.METHODS: Data from 1561 consecutive patients, who underwent coronary revascularization during a 10-month period, have been retrospectively analysed. After an univariate analysis for pre- and intraoperative risk factors, a multivariate model (logistic regression analysis) was settled.RESULTS: Preoperative use of subcutaneous/intravenous heparin, a heparin sensitivity index < 1.3 and need for a thromboendarterectomy of the left anterior descending coronary artery are independent risk factors for fatal myocardial infarction. The relative risk for fatal myocardial infarction was about 2 in the case of preoperative heparin use or heparin sensitivity index < 1.3 and 5.5 in the case of thromboendarterectomy of the left anterior descending coronary artery.CONCLUSIONS: In patients undergoing coronary artery bypass surgery, preoperative anticoagulation management with heparin may represent a risk factor for fatal myocardial infarction. Patterns of heparin resistance, whether or not due to heparin pretreatment, seem to be closely related to fatal myocardial infarction.